Studies are being conducted to further our understanding of the molecular mechanism of genetic recombination. We are carrying out genetic analyses to examine the effects of the three different Rec pathways of E. coli and the functions of their gene products on the processes of substitution type and addition type recombination. Efforts are being made to increase the frequency of transformation so that this technique can be used as an effective tool in studies on the structure and biological function of recombinant and pre-recombinant molecules. We are attempting to purify an apparent competence factor that enhances transfection in E. coli for possible use in the transformation system. In addition, studies are being undertaken to examine the cause of certain marker effects and whether different recombination pathways have any bearing on these effects.